The present disclosure relates to a sheet size setting device for setting a size of sheets stored in a sheet feeding cassette or the like, and a sheet feeding apparatus and an image forming apparatus including the same.
Image forming apparatuses such as a printer, a copier, a facsimile apparatus and a composite machine equipped with all of these functions include a sheet feeding cassette for storing a plurality of sheets that are to be subjected to image formation. Generally, a sheet feeding cassette capable of storing sheets of various sizes is detachably mounted to a main body of an image forming apparatus. Conventionally, there has been known a sheet size setting device for notifying an image forming apparatus of a size of sheets stored in a sheet feeding cassette.
The sheet size setting device is of a dial type and includes an indicator of a sheet size, and detection pattern portions each corresponding to a different size to be indicated on the indicator and capable of being identified by a specific detection sensor. A user rotates the sheet size setting device to an appropriate position according to a size of sheets stored in the sheet feeding cassette, to thereby allow the indicator to indicate the sheet size and the detection sensor to identify the sheet size.
In the above technique, the sheet size setting device is formed with a plurality of concave portions disposed in a circumferential direction, the concave portions corresponding to the different sheet sizes. One of the concave portions is brought into engagement with a protrusion disposed on the sheet feeding cassette to thereby set a position of the sheet size setting device. Further, there is a spring disposed in a compressed manner between the sheet feeding cassette and the sheet size setting device to bias the concave portion toward the protrusion. In order to change a set sheet size, a user needs to rotate the sheet size setting device against the biasing force.